1. Field of the Invention
This invention relates to apparatus for reproducing video signals from adjacent record tracks on a record medium, more particularly to comb filter apparatus for eliminating crosstalk and, more specifically, to comb filter apparatus which produces a crosstalk-eliminated delayed luminance signal.
2. Description of the Prior Art
In video signal reproducing apparatus, such as a video tape recorder (VTR), a comb filter typically is used to separate luminance and chrominance components and/or to eliminate a crosstalk component from, for example, the chrominance signal which is reproduced from the record medium. As a result, a relative time delay on the order of about one horizontal line interval (1H) is produced between the chrominance and luminance signals that are reproduced.
Since the phase of the chrominance signal is inverted at every line in a field, consistent with the NTSC standard, the phase of the chrominance signal in one track generally is opposite the phase of the chrominance signal in the same relative position in an adjacent track. Although a chrominance signal crosstalk component thus may be picked up from an adjacent track when a given track is scanned, by using a comb filter, this chrominance signal crosstalk component may be eliminated.
The use of a comb filter generally imparts a time delay to the reproduced chrominance signal, such as on the order of about H/2. When color video signals are recorded in the PAL format, the comb filter which is used to eliminate crosstalk exhibits a 2H delay. Consequently, the overall delay imparted to the chrominance signal relative to the luminance signal is on the order of about 1H.
The delay of the chrominance signal relative to the luminance signal as a result of the use of comb filters produces color deterioration in the reproduced video picture. To avoid this deterioration, it has been proposed to delay the reproduced luminance signal by an amount equal to the delay of the chrominance signal so as to equalize the delays imparted to both components. This technique of delaying the reproduced luminance signal is referred to as a delayed luminance reproduction technique, also known as Y.sub.D reproduction.
Y.sub.D reproduction generally calls for the use of a delay circuit to delay the reproduced luminance signal by an interval equal to, for example, 1H. In a typical VTR having the Y.sub.D reproduction capability, a delay circuit dedicated only for delaying the luminance component is provided. However, a special delay circuit which is used for no other purpose adds to the size and expense of the VTR electronics.